A Helmholtz Resonator-Based Acoustic Metamaterial for Power Transformer Noise Control

Sharafkhani, Naser

doi:10.1007/s40857-021-00256-z

Cited by 9 publications

(8 citation statements)

References 22 publications

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“…[20][21][22][23] Sharafkhani used Helmholtz resonators to control the transformer noise. 24 Guo et al constructed an extended neck Helmholtz resonator and studied its sound absorption capacity. 25 Jena et al demonstrated the use Helmholtz resonators around the duct experimentally, analytically, and numerically.…”

Section: Introductionmentioning

confidence: 99%

Noise isolation in building HVAC system using recyclable plastic bottles

Dogra,

Gulia,

Gupta

2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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The paper proposes an improvement of the acoustic environment in a sustainable building by utilizing differently sized discarded bottles. The HVAC (heating, ventilation and air conditioning) ducts in buildings serve as conduits for purified air, but they also generate noise as a result of turbulent flow caused by internal irregularities within the ducts. This study involves the modification in the design of ducts by utilizing the discarded or recyclable bottles. By incorporating recyclable bottles along the periphery of the duct, there is decrease in the generation of flow noise. The work presents a comprehensive investigation that employs numerical, experimental, and theoretical methods to assess the sound transmission loss (STL) within the redesigned air duct. The four-microphone impedance tube technique is utilized to measure the STL. The findings reveal that connecting bottles along the length of the air duct at specific intervals leads to a significant reduction in low-frequency noise. Additionally, increasing the number of bottles arranged radially along the air duct leads to a further enhancement and widening of the bandwidth of sound transmission loss (STL).

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Section: Introductionmentioning

confidence: 99%

Noise isolation in building HVAC system using recyclable plastic bottles

Dogra,

Gulia,

Gupta

2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…Among the present sound-absorbing materials or structures [7][8][9][10][11][12][13], acoustic metamaterials have significant advantages in controlling sound waves in the low-frequency range, and optimizing their structures can enable functionality based on new physical phenomena [14][15][16][17][18][19][20]. For example, Gao et al [14] summarized the basic classification, underlying physical mechanism, application scenarios, and emerging research trends for both passive and active noise-reduction metamaterials.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, acoustic metamaterials based on Helmholtz resonators and capable of attenuating sound up to 30 dB were developed by Casarini et al [19], which could be applied for noise control in small-scale electroacoustic devices and sensors. Furthermore, Sharafkhani [20] converted a single-band Helmholtz resonator-based sound absorber into a multi-band absorber while maintaining its thickness at 55.1 mm, and perfect absorption was realized for the main components of power transformer noise. Therefore, acoustic metamaterials have been considered as the most promising sound absorbers for noise reduction [14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Influencing Factors for Stackable and Expandable Acoustic Metamaterial with Multiple Tortuous Channels

Bi,

Yang,

Shen

et al. 2023

Materials

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To reduce the noise generated by large mechanical equipment, a stackable and expandable acoustic metamaterial with multiple tortuous channels (SEAM–MTCs) was developed in this study. The proposed SEAM–MTCs consisted of odd panels, even panels, chambers, and a final closing plate, and these component parts could be fabricated separately and then assembled. The influencing factors, including the number of layers N, the thickness of panel t0, the size of square aperture a, and the depth of chamber T0 were investigated using acoustic finite element simulation. The sound absorption mechanism was exhibited by the distributions of the total acoustic energy density at the resonance frequencies. The number of resonance frequencies increased from 13 to 31 with the number of layers N increasing from 2 to 6, and the average sound absorption coefficients in [200 Hz, 6000 Hz] was improved from 0.5169 to 0.6160. The experimental validation of actual sound absorption coefficients in [200 Hz, 1600 Hz] showed excellent consistency with simulation data, which proved the accuracy of the finite element simulation model and the reliability of the analysis of influencing factors. The proposed SEAM–MTCs has great potential in the field of equipment noise reduction.

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“…As thin flm metamaterials have advantages in low frequency bands, Yuchao et al [25] developed a membranetype acoustic metamaterial to attenuate the noise of transformers in the frequency range from 100 Hz to 500 Hz. To absorb multiple low frequency components of transformer noise, Sharafkhani [26] connected multiple Helmholtz resonators in series and parallel to obtain the perfect sound absorption at frequencies 100 Hz, 200 Hz, and 300 Hz, respectively. Ye et al [27] proposed a step-by-step structural design method to design plate-type acoustic metamaterial for transformers, which can address single-frequency and multifrequency sound insulation.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Low Frequency Bandgap of Coupled Double Beam with Quasi-Zero Stiffness for Power Transformer Vibration Control

Nie

Han

et al. 2022

Shock and Vibration

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To suppress low frequency vibration and noise generated by power transformer in residential area and achieve environment protection standards, a double-beam metamaterial is proposed, which is fabricated through periodically coupling silicon steel sheet and aluminum beams with Belleville quasi-zero stiffness spring (BQZSS). The double-beam metamaterial can be assembled with iron core of transformers as a whole to obtain the design of a low-noise transformer. Performing static analysis, the mechanical model of BQZSS is established and the relationship between restoring force, stiffness, and displacement can be obtained. Then, the mechanical properties of BQZSS are verified with the finite element method. On this basis, the governing equations of the unit cell of the double-beam metamaterial are derived using Euler–Bernoulli beam theory. According to Bloch theorem and boundary conditions, the dispersion relation of the double-beam metamaterial is deduced, and behaviors of flexural wave propagation in beams are investigated. The effects of structure parameters on bandgaps and dispersion properties are studied, and the low frequency vibration bandgap mechanism is revealed. Finally, the frequency response function (FRF) of the double-beam metamaterial with a finite length is calculated in ANSYS to verify the bandgap characteristics given by a theoretical model. The results show that the double-beam metamaterial can yield multiple low frequency bandgaps at 100 Hz, 200 Hz, 300 Hz, and 500 Hz for suppression of flexural vibration components of transformers, which benefits from Bragg scattering (BS) and the blend of BS and LR mechanisms. The opening and closing of the low frequency bandgaps and the attenuation constants within bandgaps can be tuned by choosing parameters of beams. These findings suggest that the coupling between beams can lead to novel dispersion properties, which provides a new control approach for low frequency vibration and noise in power transformer.

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A Helmholtz Resonator-Based Acoustic Metamaterial for Power Transformer Noise Control

Cited by 9 publications

References 22 publications

Noise isolation in building HVAC system using recyclable plastic bottles

Noise isolation in building HVAC system using recyclable plastic bottles

Analysis of Influencing Factors for Stackable and Expandable Acoustic Metamaterial with Multiple Tortuous Channels

Investigation on Low Frequency Bandgap of Coupled Double Beam with Quasi-Zero Stiffness for Power Transformer Vibration Control

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